/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.apksig.internal.jar;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.jar.Attributes;
/**
* JAR manifest and signature file parser.
*
* <p>These files consist of a main section followed by individual sections. Individual sections
* are named, their names referring to JAR entries.
*
* @see <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#JAR_Manifest">JAR Manifest format</a>
*/
public class ManifestParser {
private final byte[] mManifest;
private int mOffset;
private int mEndOffset;
private byte[] mBufferedLine;
/**
* Constructs a new {@code ManifestParser} with the provided input.
*/
public ManifestParser(byte[] data) {
this(data, 0, data.length);
}
/**
* Constructs a new {@code ManifestParser} with the provided input.
*/
public ManifestParser(byte[] data, int offset, int length) {
mManifest = data;
mOffset = offset;
mEndOffset = offset + length;
}
/**
* Returns the remaining sections of this file.
*/
public List<Section> readAllSections() {
List<Section> sections = new ArrayList<>();
Section section;
while ((section = readSection()) != null) {
sections.add(section);
}
return sections;
}
/**
* Returns the next section from this file or {@code null} if end of file has been reached.
*/
public Section readSection() {
// Locate the first non-empty line
int sectionStartOffset;
String attr;
do {
sectionStartOffset = mOffset;
attr = readAttribute();
if (attr == null) {
return null;
}
} while (attr.length() == 0);
List<Attribute> attrs = new ArrayList<>();
attrs.add(parseAttr(attr));
// Read attributes until end of section reached
while (true) {
attr = readAttribute();
if ((attr == null) || (attr.length() == 0)) {
// End of section
break;
}
attrs.add(parseAttr(attr));
}
int sectionEndOffset = mOffset;
int sectionSizeBytes = sectionEndOffset - sectionStartOffset;
return new Section(sectionStartOffset, sectionSizeBytes, attrs);
}
private static Attribute parseAttr(String attr) {
// Name is separated from value by a semicolon followed by a single SPACE character.
// This permits trailing spaces in names and leading and trailing spaces in values.
// Some APK obfuscators take advantage of this fact. We thus need to preserve these unusual
// spaces to be able to parse such obfuscated APKs.
int delimiterIndex = attr.indexOf(": ");
if (delimiterIndex == -1) {
return new Attribute(attr, "");
} else {
return new Attribute(
attr.substring(0, delimiterIndex),
attr.substring(delimiterIndex + ": ".length()));
}
}
/**
* Returns the next attribute or empty {@code String} if end of section has been reached or
* {@code null} if end of input has been reached.
*/
private String readAttribute() {
byte[] bytes = readAttributeBytes();
if (bytes == null) {
return null;
} else if (bytes.length == 0) {
return "";
} else {
return new String(bytes, StandardCharsets.UTF_8);
}
}
/**
* Returns the next attribute or empty array if end of section has been reached or {@code null}
* if end of input has been reached.
*/
private byte[] readAttributeBytes() {
// Check whether end of section was reached during previous invocation
if ((mBufferedLine != null) && (mBufferedLine.length == 0)) {
mBufferedLine = null;
return EMPTY_BYTE_ARRAY;
}
// Read the next line
byte[] line = readLine();
if (line == null) {
// End of input
if (mBufferedLine != null) {
byte[] result = mBufferedLine;
mBufferedLine = null;
return result;
}
return null;
}
// Consume the read line
if (line.length == 0) {
// End of section
if (mBufferedLine != null) {
byte[] result = mBufferedLine;
mBufferedLine = EMPTY_BYTE_ARRAY;
return result;
}
return EMPTY_BYTE_ARRAY;
}
byte[] attrLine;
if (mBufferedLine == null) {
attrLine = line;
} else {
if ((line.length == 0) || (line[0] != ' ')) {
// The most common case: buffered line is a full attribute
byte[] result = mBufferedLine;
mBufferedLine = line;
return result;
}
attrLine = mBufferedLine;
mBufferedLine = null;
attrLine = concat(attrLine, line, 1, line.length - 1);
}
// Everything's buffered in attrLine now. mBufferedLine is null
// Read more lines
while (true) {
line = readLine();
if (line == null) {
// End of input
return attrLine;
} else if (line.length == 0) {
// End of section
mBufferedLine = EMPTY_BYTE_ARRAY; // return "end of section" next time
return attrLine;
}
if (line[0] == ' ') {
// Continuation line
attrLine = concat(attrLine, line, 1, line.length - 1);
} else {
// Next attribute
mBufferedLine = line;
return attrLine;
}
}
}
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
private static byte[] concat(byte[] arr1, byte[] arr2, int offset2, int length2) {
byte[] result = new byte[arr1.length + length2];
System.arraycopy(arr1, 0, result, 0, arr1.length);
System.arraycopy(arr2, offset2, result, arr1.length, length2);
return result;
}
/**
* Returns the next line (without line delimiter characters) or {@code null} if end of input has
* been reached.
*/
private byte[] readLine() {
if (mOffset >= mEndOffset) {
return null;
}
int startOffset = mOffset;
int newlineStartOffset = -1;
int newlineEndOffset = -1;
for (int i = startOffset; i < mEndOffset; i++) {
byte b = mManifest[i];
if (b == '\r') {
newlineStartOffset = i;
int nextIndex = i + 1;
if ((nextIndex < mEndOffset) && (mManifest[nextIndex] == '\n')) {
newlineEndOffset = nextIndex + 1;
break;
}
newlineEndOffset = nextIndex;
break;
} else if (b == '\n') {
newlineStartOffset = i;
newlineEndOffset = i + 1;
break;
}
}
if (newlineStartOffset == -1) {
newlineStartOffset = mEndOffset;
newlineEndOffset = mEndOffset;
}
mOffset = newlineEndOffset;
if (newlineStartOffset == startOffset) {
return EMPTY_BYTE_ARRAY;
}
return Arrays.copyOfRange(mManifest, startOffset, newlineStartOffset);
}
/**
* Attribute.
*/
public static class Attribute {
private final String mName;
private final String mValue;
/**
* Constructs a new {@code Attribute} with the provided name and value.
*/
public Attribute(String name, String value) {
mName = name;
mValue = value;
}
/**
* Returns this attribute's name.
*/
public String getName() {
return mName;
}
/**
* Returns this attribute's value.
*/
public String getValue() {
return mValue;
}
}
/**
* Section.
*/
public static class Section {
private final int mStartOffset;
private final int mSizeBytes;
private final String mName;
private final List<Attribute> mAttributes;
/**
* Constructs a new {@code Section}.
*
* @param startOffset start offset (in bytes) of the section in the input file
* @param sizeBytes size (in bytes) of the section in the input file
* @param attrs attributes contained in the section
*/
public Section(int startOffset, int sizeBytes, List<Attribute> attrs) {
mStartOffset = startOffset;
mSizeBytes = sizeBytes;
String sectionName = null;
if (!attrs.isEmpty()) {
Attribute firstAttr = attrs.get(0);
if ("Name".equalsIgnoreCase(firstAttr.getName())) {
sectionName = firstAttr.getValue();
}
}
mName = sectionName;
mAttributes = Collections.unmodifiableList(new ArrayList<>(attrs));
}
public String getName() {
return mName;
}
/**
* Returns the offset (in bytes) at which this section starts in the input.
*/
public int getStartOffset() {
return mStartOffset;
}
/**
* Returns the size (in bytes) of this section in the input.
*/
public int getSizeBytes() {
return mSizeBytes;
}
/**
* Returns this section's attributes, in the order in which they appear in the input.
*/
public List<Attribute> getAttributes() {
return mAttributes;
}
/**
* Returns the value of the specified attribute in this section or {@code null} if this
* section does not contain a matching attribute.
*/
public String getAttributeValue(Attributes.Name name) {
return getAttributeValue(name.toString());
}
/**
* Returns the value of the specified attribute in this section or {@code null} if this
* section does not contain a matching attribute.
*
* @param name name of the attribute. Attribute names are case-insensitive.
*/
public String getAttributeValue(String name) {
for (Attribute attr : mAttributes) {
if (attr.getName().equalsIgnoreCase(name)) {
return attr.getValue();
}
}
return null;
}
}
}
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